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//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Chris Lattner and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This contains code to emit Aggregate Expr nodes as LLVM code.
//
//===----------------------------------------------------------------------===//
#include "CodeGenFunction.h"
#include "CodeGenModule.h"
#include "clang/AST/AST.h"
#include "llvm/Constants.h"
#include "llvm/Function.h"
#include "llvm/Support/Compiler.h"
using namespace clang;
using namespace CodeGen;
//===----------------------------------------------------------------------===//
// Aggregate Expression Emitter
//===----------------------------------------------------------------------===//
namespace {
class VISIBILITY_HIDDEN AggExprEmitter : public StmtVisitor<AggExprEmitter> {
CodeGenFunction &CGF;
llvm::LLVMBuilder &Builder;
llvm::Value *DestPtr;
bool VolatileDest;
public:
AggExprEmitter(CodeGenFunction &cgf, llvm::Value *destPtr, bool volatileDest)
: CGF(cgf), Builder(CGF.Builder),
DestPtr(destPtr), VolatileDest(volatileDest) {
}
//===--------------------------------------------------------------------===//
// Utilities
//===--------------------------------------------------------------------===//
/// EmitAggLoadOfLValue - Given an expression with aggregate type that
/// represents a value lvalue, this method emits the address of the lvalue,
/// then loads the result into DestPtr.
void EmitAggLoadOfLValue(const Expr *E);
void EmitAggregateCopy(llvm::Value *DestPtr, llvm::Value *SrcPtr,
QualType EltTy);
//===--------------------------------------------------------------------===//
// Visitor Methods
//===--------------------------------------------------------------------===//
void VisitStmt(Stmt *S) {
fprintf(stderr, "Unimplemented agg expr!\n");
S->dump(CGF.getContext().SourceMgr);
}
void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
// l-values.
void VisitDeclRefExpr(DeclRefExpr *DRE) { return EmitAggLoadOfLValue(DRE); }
// case Expr::ArraySubscriptExprClass:
// Operators.
// case Expr::UnaryOperatorClass:
// case Expr::ImplicitCastExprClass:
// case Expr::CastExprClass:
// case Expr::CallExprClass:
void VisitStmtExpr(const StmtExpr *E);
void VisitBinaryOperator(const BinaryOperator *BO);
void VisitBinAssign(const BinaryOperator *E);
void VisitConditionalOperator(const ConditionalOperator *CO);
// case Expr::ChooseExprClass:
};
} // end anonymous namespace.
//===----------------------------------------------------------------------===//
// Utilities
//===----------------------------------------------------------------------===//
void AggExprEmitter::EmitAggregateCopy(llvm::Value *DestPtr,
llvm::Value *SrcPtr, QualType Ty) {
assert(!Ty->isComplexType() && "Shouldn't happen for complex");
// Aggregate assignment turns into llvm.memcpy.
const llvm::Type *BP = llvm::PointerType::get(llvm::Type::Int8Ty);
if (DestPtr->getType() != BP)
DestPtr = Builder.CreateBitCast(DestPtr, BP, "tmp");
if (SrcPtr->getType() != BP)
SrcPtr = Builder.CreateBitCast(SrcPtr, BP, "tmp");
// Get size and alignment info for this aggregate.
std::pair<uint64_t, unsigned> TypeInfo =
CGF.getContext().getTypeInfo(Ty, SourceLocation());
// FIXME: Handle variable sized types.
const llvm::Type *IntPtr = llvm::IntegerType::get(CGF.LLVMPointerWidth);
llvm::Value *MemCpyOps[4] = {
DestPtr, SrcPtr,
llvm::ConstantInt::get(IntPtr, TypeInfo.first),
llvm::ConstantInt::get(llvm::Type::Int32Ty, TypeInfo.second)
};
Builder.CreateCall(CGF.CGM.getMemCpyFn(), MemCpyOps, MemCpyOps+4);
}
/// EmitAggLoadOfLValue - Given an expression with aggregate type that
/// represents a value lvalue, this method emits the address of the lvalue,
/// then loads the result into DestPtr.
void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
LValue LV = CGF.EmitLValue(E);
assert(LV.isSimple() && "Can't have aggregate bitfield, vector, etc");
llvm::Value *SrcPtr = LV.getAddress();
// If the result is ignored, don't copy from the value.
if (DestPtr == 0)
// FIXME: If the source is volatile, we must read from it.
return;
EmitAggregateCopy(DestPtr, SrcPtr, E->getType());
}
//===----------------------------------------------------------------------===//
// Visitor Methods
//===----------------------------------------------------------------------===//
void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
CGF.EmitCompoundStmt(*E->getSubStmt(), true, DestPtr, VolatileDest);
}
void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
fprintf(stderr, "Unimplemented aggregate binary expr!\n");
E->dump(CGF.getContext().SourceMgr);
}
void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
assert(E->getLHS()->getType().getCanonicalType() ==
E->getRHS()->getType().getCanonicalType() && "Invalid assignment");
LValue LHS = CGF.EmitLValue(E->getLHS());
// Codegen the RHS so that it stores directly into the LHS.
CGF.EmitAggExpr(E->getRHS(), LHS.getAddress(), false /*FIXME: VOLATILE LHS*/);
// If the result of the assignment is used, copy the RHS there also.
if (DestPtr) {
assert(0 && "FIXME: Chained agg assignment not implemented yet");
}
}
void AggExprEmitter::VisitConditionalOperator(const ConditionalOperator *E) {
llvm::BasicBlock *LHSBlock = new llvm::BasicBlock("cond.?");
llvm::BasicBlock *RHSBlock = new llvm::BasicBlock("cond.:");
llvm::BasicBlock *ContBlock = new llvm::BasicBlock("cond.cont");
llvm::Value *Cond = CGF.EvaluateExprAsBool(E->getCond());
Builder.CreateCondBr(Cond, LHSBlock, RHSBlock);
CGF.EmitBlock(LHSBlock);
// Handle the GNU extension for missing LHS.
assert(E->getLHS() && "Must have LHS for aggregate value");
Visit(E->getLHS());
Builder.CreateBr(ContBlock);
LHSBlock = Builder.GetInsertBlock();
CGF.EmitBlock(RHSBlock);
Visit(E->getRHS());
Builder.CreateBr(ContBlock);
RHSBlock = Builder.GetInsertBlock();
CGF.EmitBlock(ContBlock);
}
//===----------------------------------------------------------------------===//
// Entry Points into this File
//===----------------------------------------------------------------------===//
/// EmitAggExpr - Emit the computation of the specified expression of
/// aggregate type. The result is computed into DestPtr. Note that if
/// DestPtr is null, the value of the aggregate expression is not needed.
void CodeGenFunction::EmitAggExpr(const Expr *E, llvm::Value *DestPtr,
bool VolatileDest) {
assert(E && hasAggregateLLVMType(E->getType()) &&
"Invalid aggregate expression to emit");
AggExprEmitter(*this, DestPtr, VolatileDest).Visit(const_cast<Expr*>(E));
}
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